Go to Post We'll see how this goes... it could be fun. - Andy Baker [more]
Home
Go Back   Chief Delphi > Technical > Technical Discussion
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
 
 
Thread Tools Rate Thread Display Modes
Prev Previous Post   Next Post Next
  #17   Spotlight this post!  
Unread 31-12-2006, 16:48
DonRotolo's Avatar
DonRotolo DonRotolo is offline
Back to humble
FRC #0832
Team Role: Mentor
 
Join Date: Jan 2005
Rookie Year: 2005
Location: Atlanta GA
Posts: 7,025
DonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond repute
Re: Threaded rod through ball bearings

Madison, the two issues are both related to the threads:

1. The effect of the threads as stress concentrators on the rod. However, if the rod it thick enough, that is, not near it's strength limits, there isn't much to worry about..

2. The effect of the relatively small contact area between the rod and the bearing ID - that is, will the threads mush down from the force? You need to know the force (in PSI) on the thread tips from the bearing, and run that against the yield strength of the thread material (steel?) and if they're on the same order of magnitude, it's a problem. But, consider a 120 lb robot, maybe 10G force, and 0.2 SqIn of contact area (=6000 PSI) at 40,000 kPSI Yield, you're safe. (The contact area is very conservative here - it is likely more, and thus even better). I also ignored that there are two bearings, each taking about half the load, etc.

(There is another effect, the threads and their reaction to torque, but the effect is small compared to the capacity of the rod, and so can be ignored)

So, back of the napkin, seems OK.

Don
__________________

I am N2IRZ - What's your callsign?
 


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Rod-Less Cylider??? sgsdragons Pneumatics 4 24-01-2005 19:55
threaded rod Mercutio OCCRA 3 28-09-2003 20:45
Drills: The ball bearings are gone? BobbyG Motors 0 21-01-2003 23:57
threaded rod fasteners... archiver 2001 1 24-06-2002 00:08
threaded rod? RobDeCotiis Kit & Additional Hardware 4 18-02-2002 12:21


All times are GMT -5. The time now is 16:59.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi